Answer:

Explanation:
Given that,
The mass of a golf ball, m = 40 g = 0.04 kg
Its angular velocity, 
The radius of the sphere is 2.5 cm or 0.025 m
We need to find the magnitude of the angular momentum of the ball. It is given by the formula as follows:

Where I is moment of inertia
For sphere, 

So, the magnitude of the angular momentum of the sphere is
.
Answer:
Explanation:
The energy of a photon is given by the equation
, where h is the <em>Planck constant</em> and f the frequency of the photon. Thus, N photons of frequency f will give an energy of
.
We also know that frequency and wavelength are related by
, so we have
, where c is the <em>speed of light</em>.
We will want the number of photons, so we can write

We need to know then how much energy do we have to calculate N. The equation of power is
, so for the power we have and considering 1 second we can calculate the total energy, and then only consider the 4% of it which will produce light, or better said, the N photons, which means it will be
.
Putting this paragraph in equations:
.
And then we can substitute everything in our equation for number of photons, in S.I. and getting the values of constants from tables:

A big part of the reason that mirrors are seldom if ever used to generate
electricity is the simple fact that there is no way to generate electricity using
mirrors. They are as useless for the purpose as smoke is, although there are
those who have used both items simultaneously to create the impression that
they have succeeded in that attempt.
Choice-'b' says the formula for kinetic energy in words.
KE = (1/2) · (M) · (S²)